Systems and methods for reducing collisions after traffic indication map paging

ABSTRACT

Systems, methods, and devices for reducing collisions in a wireless communications network are described herein. In some aspects, a receiver receives a paging message. The paging message includes an ordering and a multiplier. A processor determines a first wake-up time based on the ordering and the multiplier. The wireless device wakes up at the determined wake-up time. The wireless device receives data via the receiver.

BACKGROUND

1. Field

The present application relates generally to wireless communications,and more specifically to systems, methods, and devices for performingcollision avoidance in a wireless communication network.

2. Background

In many telecommunication systems, communications networks are used toexchange messages among several interacting spatially-separated devices.Networks can be classified according to geographic scope, which couldbe, for example, a metropolitan area, a local area, or a personal area.Such networks would be designated respectively as a wide area network(WAN), metropolitan area network (MAN), local area network (LAN),wireless local area network (WLAN), or personal area network (PAN).Networks also differ according to the switching/routing technique usedto interconnect the various network nodes and devices (e.g., circuitswitching vs. packet switching), the type of physical media employed fortransmission (e.g., wired vs. wireless), and the set of communicationprotocols used (e.g., Internet protocol suite, SONET (SynchronousOptical Networking), Ethernet, etc.).

Wireless networks are often preferred when the network elements aremobile and thus have dynamic connectivity needs, or if the networkarchitecture is formed in an ad hoc, rather than fixed, topology.Wireless networks employ intangible physical media in an unguidedpropagation mode using electromagnetic waves in the radio, microwave,infra-red, optical, etc. frequency bands. Wireless networksadvantageously facilitate user mobility and rapid field deployment whencompared to fixed wired networks.

The devices in a wireless network can transmit/receive informationbetween each other. Further, devices that are not activelytransmitting/receiving information in the wireless network can enter adoze state to conserve power, where the devices do not activelytransmit/receive information in the doze state. These devices canfurther utilize paging messages to determine when to wake up from a dozestate and enter an awake state in order to transmit/receive data. Thus,improved systems, methods, and devices for reducing collisions aredesired.

SUMMARY

The systems, methods, and devices of the invention each have severalaspects, no single one of which is solely responsible for its desirableattributes. Without limiting the scope of this invention as expressed bythe claims which follow, some features will now be discussed briefly.After considering this discussion, and particularly after reading thesection entitled “Detailed Description” one will understand how thefeatures of this invention provide advantages that include improvedpaging for devices in a wireless network.

One aspect of this disclosure provides a method for reducing collisionsin a wireless communications network. The method includes receiving, ata wireless device, a paging message. The paging message includes anordering and a multiplier. The method further includes determining afirst wake-up time based on the ordering and the multiplier. The methodfurther includes waking up at the determined wake-up time. The methodfurther includes receiving data.

In an embodiment, the method can further include transmitting a requestfor the data. The method can further include determining a secondwake-up time. The method can further include waking up at the determinedsecond wake-up time. The method can further include receiving anacknowledgement to the request for data. The second wake-up time can beearlier than the first wake-up time.

Another aspect of this disclosure provides a wireless device configuredto reduce collisions in a wireless communications network. The wirelessdevice includes a receiver configured to receive a paging message. Thepaging message includes an ordering and a multiplier. The wirelessdevice further includes a processor configured to determine a firstwake-up time based on the ordering and the multiplier. The processor isfurther configured to wake up at the determined wake-up time. Theprocessor is further configured to receive data.

In an embodiment, the wireless device can further include a transmitterconfigured to transmit a request for the data. The processor can befurther configured to determine a second wake-up time. The processor canbe further configured to wake up at the determined second wake-up time.The receiver can be further configured to receive an acknowledgement tothe request for data. The second wake-up time can be earlier than thefirst wake-up time.

Another aspect of this disclosure provides an apparatus for reducingcollisions in a wireless communications network. The apparatus includesmeans for receiving a paging message. The paging message includes anordering and a multiplier. The apparatus further includes means fordetermining a first wake-up time based on the ordering and themultiplier. The apparatus further includes means for waking up at thedetermined wake-up time. The apparatus further includes means forreceiving data.

In an embodiment, the apparatus can further include means fortransmitting a request for the data. The apparatus can further includemeans for determining a second wake-up time. The apparatus can furtherinclude means for waking up at the determined second wake-up time. Theapparatus can further include means for receiving an acknowledgement tothe request for data. The second wake-up time can be earlier than thefirst wake-up time.

Another aspect of this disclosure provides a non-transitorycomputer-readable medium. The medium includes code that, when executedby one or more processors, causes an apparatus to receive a pagingmessage. The paging message includes an ordering and a multiplier. Themedium further includes code that, when executed by one or moreprocessors, causes the apparatus to determine a first wake-up time basedon the ordering and the multiplier. The medium further includes codethat, when executed by one or more processors, causes the apparatus towake up at the determined wake-up time. The medium further includes codethat, when executed by one or more processors, causes the apparatus toreceive data.

In an embodiment, the medium can further include code that, whenexecuted by one or more processors, causes the apparatus to transmit arequest for the data. The medium can further include code that, whenexecuted by one or more processors, causes the apparatus to determine asecond wake-up time. The medium can further include code that, whenexecuted by one or more processors, causes the apparatus to wake up atthe determined second wake-up time. The medium can further include codethat, when executed by one or more processors, causes the apparatus toreceive an acknowledgement to the request for data. The second wake-uptime can be earlier than the first wake-up time.

Another aspect of this disclosure provides a method for reducingcollisions in a wireless communications network. The method includestransmitting, at a wireless device, an advertisement of an extendedsleep mode. The method further includes sleeping through one or morepaging messages of an access point. The method further includestransmitting a request for data. The method further includes receivingdata.

Another aspect of this disclosure provides a wireless device forreducing collisions in a wireless communications network. The deviceincludes a transmitter configured to transmit an advertisement of anextended sleep mode. The device further includes a processor configuredto sleep through one or more paging messages of an access point. Thetransmitter is further configured to transmit a request for data. Thedevice further includes a receiver configured to receive data.

Another aspect of this disclosure provides an apparatus for reducingcollisions in a wireless communications network. The apparatus includesmeans for transmitting an advertisement of an extended sleep mode. Theapparatus further includes means for sleeping through one or more pagingmessages of an access point. The apparatus further includes means fortransmitting a request for data. The apparatus further includes meansfor receiving data.

Another aspect of this disclosure provides a non-transitorycomputer-readable medium. The medium includes code that, when executedby one or more processors, causes an apparatus to transmit anadvertisement of an extended sleep mode. The medium further includescode that, when executed by one or more processors, causes the apparatusto sleep through one or more paging messages of an access point. Themedium further includes code that, when executed by one or moreprocessors, causes the apparatus to transmit a request for data. Themedium further includes code that, when executed by one or moreprocessors, causes the apparatus to receive data.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exemplary wireless communication system in which aspectsof the present disclosure can be employed.

FIG. 2 shows a functional block diagram of an exemplary wireless devicethat can be employed within the wireless communication system of FIG. 1.

FIG. 3 illustrates a plurality of partitioned paging messagestransmitted by an access point to wireless stations in the wirelesscommunication system of FIG. 1.

FIG. 4 illustrates an exemplary polling request mechanism.

FIG. 5A illustrates another exemplary polling request mechanism.

FIG. 5B illustrates another exemplary polling request mechanism.

FIG. 6 illustrates an exemplary non-polling mechanism.

FIG. 7 is a flowchart of a process for reducing collisions in thewireless communication system of FIG. 1.

FIG. 8 is a functional block diagram of an exemplary wireless devicethat can be employed within the wireless communication system of FIG. 1.

DETAILED DESCRIPTION

Various aspects of the novel systems, apparatuses, and methods aredescribed more fully hereinafter with reference to the accompanyingdrawings. This disclosure can, however, be embodied in many differentforms and should not be construed as limited to any specific structureor function presented throughout this disclosure. Rather, these aspectsare provided so that this disclosure will be thorough and complete, andwill fully convey the scope of the disclosure to those skilled in theart. Based on the teachings herein one skilled in the art shouldappreciate that the scope of the disclosure is intended to cover anyaspect of the novel systems, apparatuses, and methods disclosed herein,whether implemented independently of, or combined with, any other aspectof the invention. For example, an apparatus can be implemented or amethod can be practiced using any number of the aspects set forthherein. In addition, the scope of the invention is intended to coversuch an apparatus or method which is practiced using other structure,functionality, or structure and functionality in addition to or otherthan the various aspects of the invention set forth herein. It should beunderstood that any aspect disclosed herein can be embodied by one ormore elements of a claim.

Although particular aspects are described herein, many variations andpermutations of these aspects fall within the scope of the disclosure.Although some benefits and advantages of the preferred aspects arementioned, the scope of the disclosure is not intended to be limited toparticular benefits, uses, or objectives. Rather, aspects of thedisclosure are intended to be broadly applicable to different wirelesstechnologies, system configurations, networks, and transmissionprotocols, some of which are illustrated by way of example in thefigures and in the following description of the preferred aspects. Thedetailed description and drawings are merely illustrative of thedisclosure rather than limiting, the scope of the disclosure beingdefined by the appended claims and equivalents thereof.

Popular wireless network technologies can include various types ofwireless local area networks (WLANs). A WLAN can be used to interconnectnearby devices together, employing widely used networking protocols. Thevarious aspects described herein can apply to any communicationstandard, such as a wireless protocol.

In some aspects, wireless signals in a sub-gigahertz band can betransmitted according to the 802.11ah protocol using orthogonalfrequency-division multiplexing (OFDM), direct-sequence spread spectrum(DSSS) communications, a combination of OFDM and DSSS communications, orother schemes. Implementations of the 802.11ah protocol can be used forsensors, metering, and smart grid networks. Advantageously, aspects ofcertain devices implementing the 802.11ah protocol can consume lesspower than devices implementing other wireless protocols, and/or can beused to transmit wireless signals across a relatively long range, forexample about one kilometer or longer.

In some implementations, a WLAN includes various devices which are thecomponents that access the wireless network. For example, there can betwo types of devices: access points (“APs”) and clients (also referredto as stations, or “STAB”). In general, an AP can serve as a hub or basestation for the WLAN and an STA serves as a user of the WLAN. Forexample, an STA can be a laptop computer, a personal digital assistant(PDA), a mobile phone, etc. In an example, an STA connects to an AP viaa WiFi (e.g., IEEE 802.11 protocol such as 802.11ah) compliant wirelesslink to obtain general connectivity to the Internet or to other widearea networks. In some implementations an STA can also be used as an AP.

An access point (“AP”) can also include, be implemented as, or known asa NodeB, Radio Network Controller (“RNC”), eNodeB, Base StationController (“BSC”), Base Transceiver Station (“BTS”), Base Station(“BS”), Transceiver Function (“TF”), Radio Router, Radio Transceiver, orsome other terminology.

A station “STA” can also include, be implemented as, or known as anaccess terminal (“AT”), a subscriber station, a subscriber unit, amobile station, a remote station, a remote terminal, a user terminal, auser agent, a user device, user equipment, or some other terminology. Insome implementations an access terminal can include a cellulartelephone, a cordless telephone, a Session Initiation Protocol (“SIP”)phone, a wireless local loop (“WLL”) station, a personal digitalassistant (“PDA”), a handheld device having wireless connectioncapability, or some other suitable processing device connected to awireless modem. Accordingly, one or more aspects taught herein can beincorporated into a phone (e.g., a cellular phone or smartphone), acomputer (e.g., a laptop), a portable communication device, a headset, aportable computing device (e.g., a personal data assistant), anentertainment device (e.g., a music or video device, or a satelliteradio), a gaming device or system, a global positioning system device,or any other suitable device that is configured to communicate via awireless medium.

As discussed above, certain of the devices described herein canimplement the 802.11ah standard, for example. Such devices, whether usedas an STA or AP or other device, can be used for smart metering or in asmart grid network. Such devices can provide sensor applications or beused in home automation. The devices can instead or in addition be usedin a healthcare context, for example for personal healthcare. They canalso be used for surveillance, to enable extended-range Internetconnectivity (e.g., for use with hotspots), or to implementmachine-to-machine communications.

FIG. 1 shows an exemplary wireless communication system 100 in whichaspects of the present disclosure can be employed. The wirelesscommunication system 100 can operate pursuant to a wireless standard,for example the 802.11ah standard. The wireless communication system 100can include an AP 104, which communicates with STAs 106.

A variety of processes and methods can be used for transmissions in thewireless communication system 100 between the AP 104 and the STAs 106.For example, signals can be sent and received between the AP 104 and theSTAs 106 in accordance with OFDM/OFDMA techniques. If this is the case,the wireless communication system 100 can be referred to as anOFDM/OFDMA system. Alternatively, signals can be sent and receivedbetween the AP 104 and the STAs 106 in accordance with CDMA techniques.If this is the case, the wireless communication system 100 can bereferred to as a CDMA system.

A communication link that facilitates transmission from the AP 104 toone or more of the STAs 106 can be referred to as a downlink (DL) 108,and a communication link that facilitates transmission from one or moreof the STAs 106 to the AP 104 can be referred to as an uplink (UL) 110.Alternatively, a downlink 108 can be referred to as a forward link or aforward channel, and an uplink 110 can be referred to as a reverse linkor a reverse channel.

The AP 104 can act as a base station and provide wireless communicationcoverage in a basic service area (BSA) 102. The AP 104 along with theSTAs 106 associated with the AP 104 and that use the AP 104 forcommunication can be referred to as a basic service set (BSS). It shouldbe noted that the wireless communication system 100 may not have acentral AP 104, but rather can function as a peer-to-peer networkbetween the STAs 106. Accordingly, the functions of the AP 104 describedherein can alternatively be performed by one or more of the STAs 106.

The AP 104 can transmit a beacon signal (or simply a “beacon”), via acommunication link such as the downlink 108, to other nodes STAs 106 ofthe system 100, which can help the other nodes STAs 106 to synchronizetheir timing with the AP 104, or which can provide other information orfunctionality. Such beacons can be transmitted periodically. In oneaspect, the period between successive transmissions can be referred toas a superframe. Transmission of a beacon can be divided into a numberof groups or intervals. In one aspect, the beacon can include, but isnot limited to, such information as timestamp information to set acommon clock, a peer-to-peer network identifier, a device identifier,capability information, a superframe duration, transmission directioninformation, reception direction information, a neighbor list, and/or anextended neighbor list, some of which are described in additional detailbelow. Thus, a beacon can include information both common (e.g., shared)amongst several devices, and information specific to a given device.

In some aspects, a STA 106 can be required to associate with the AP 104in order to send communications to and/or receive communications fromthe AP 104. In one aspect, information for associating is included in abeacon broadcast by the AP 104. To receive such a beacon, the STA 106can, for example, perform a broad coverage search over a coverageregion. A search can also be performed by the STA 106 by sweeping acoverage region in a lighthouse fashion, for example. After receivingthe information for associating, the STA 106 can transmit a referencesignal, such as an association probe or request, to the AP 104. In someaspects, the AP 104 can use backhaul services, for example, tocommunicate with a larger network, such as the Internet or a publicswitched telephone network (PSTN).

FIG. 2 shows an exemplary functional block diagram of a wireless device202 that can be employed within the wireless communication system 100 ofFIG. 1. The wireless device 202 is an example of a device that can beconfigured to implement the various methods described herein. Forexample, the wireless device 202 can include the AP 104 or one of theSTAs 106.

The wireless device 202 can include a processor 204 which controlsoperation of the wireless device 202. The processor 204 can also bereferred to as a central processing unit (CPU). Memory 206, which caninclude both read-only memory (ROM) and random access memory (RAM), canprovide instructions and data to the processor 204. A portion of thememory 206 can also include non-volatile random access memory (NVRAM).The processor 204 typically performs logical and arithmetic operationsbased on program instructions stored within the memory 206. Theinstructions in the memory 206 can be executable to implement themethods described herein.

The processor 204 can include or be a component of a processing systemimplemented with one or more processors. The one or more processors canbe implemented with any combination of general-purpose microprocessors,microcontrollers, digital signal processors (DSPs), field programmablegate array (FPGAs), programmable logic devices (PLDs), controllers,state machines, gated logic, discrete hardware components, dedicatedhardware finite state machines, or any other suitable entities that canperform calculations or other manipulations of information.

The processing system can also include machine-readable media forstoring software. Software shall be construed broadly to mean any typeof instructions, whether referred to as software, firmware, middleware,microcode, hardware description language, or otherwise. Instructions caninclude code (e.g., in source code format, binary code format,executable code format, or any other suitable format of code). Theinstructions, when executed by the one or more processors, cause theprocessing system to perform the various functions described herein.

The wireless device 202 can also include a housing 208 that can includea transmitter 210 and/or a receiver 212 to allow transmission andreception of data between the wireless device 202 and a remote location.The transmitter 210 and receiver 212 can be combined into a transceiver214. An antenna 216 can be attached to the housing 208 and electricallycoupled to the transceiver 214. The wireless device 202 can also include(not shown) multiple transmitters, multiple receivers, multipletransceivers, and/or multiple antennas.

The transmitter 210 can be configured to wirelessly transmit messages,which can be referred to as “paging messages” that are configured toindicate to wireless devices whether or not the wireless devices need towake up from a doze state and enter an awake state as discussed below.For example, the transmitter 210 can be configured to transmit pagingmessages generated by the processor 204, discussed above. When thewireless device 202 is implemented or used as a STA 106, the processor204 can be configured to process paging messages. When the wirelessdevice 202 is implemented or used as an AP 104, the processor 204 canalso be configured to generate paging messages.

The receiver 212 can be configured to wirelessly receive pagingmessages. When the wireless device 202 is implemented or used as a STA106, the transmitter 210 can be configured to transmit requests for datain response to the paging messages. For example, the wireless device 202can be configured to transmit a Power-Saving Poll (PS-Poll) as will bedescribed herein with respect to FIG. 4. When the wireless device 202 isimplemented or used as an AP 104, the transmitter 210 can be furtherconfigured to transmit data to the one or more STAs 106. When thewireless device 202 is implemented or used as a STA 106, the transmitter210 can be configured to transmit an acknowledgement to the datareceived from the AP 104.

The wireless device 202 can also include a signal detector 218 that canbe used in an effort to detect and quantify the level of signalsreceived by the transceiver 214. The signal detector 218 can detect suchsignals as total energy, energy per subcarrier per symbol, powerspectral density and other signals. The wireless device 202 can alsoinclude a digital signal processor (DSP) 220 for use in processingsignals. The DSP 220 can be configured to generate a packet fortransmission. In some aspects, the packet can include a physical layerdata unit (PPDU).

The wireless device 202 can further include a user interface 222 in someaspects. The user interface 222 can include a keypad, a microphone, aspeaker, and/or a display. The user interface 222 can include anyelement or component that conveys information to a user of the wirelessdevice 202 and/or receives input from the user.

The various components of the wireless device 202 can be coupledtogether by a bus system 226. The bus system 226 can include a data bus,for example, as well as a power bus, a control signal bus, and a statussignal bus in addition to the data bus. Those of skill in the art willappreciate the components of the wireless device 202 can be coupledtogether or accept or provide inputs to each other using some othermechanism.

Although a number of separate components are illustrated in FIG. 2,those of skill in the art will recognize that one or more of thecomponents can be combined or commonly implemented. For example, theprocessor 204 can be used to implement not only the functionalitydescribed above with respect to the processor 204, but also to implementthe functionality described above with respect to the signal detector218 and/or the DSP 220. Further, each of the components illustrated inFIG. 2 can be implemented using a plurality of separate elements.

The wireless device 202 can include an AP 104 or an STA 106, and can beused to transmit and/or receive communications including pagingmessages. That is, either AP 104 or STA 106 can serve as transmitter orreceiver devices of paging messages. Certain aspects contemplate signaldetector 218 being used by software running on memory 206 and processor204 to detect the presence of a transmitter or receiver.

The STA 106 can have a plurality of operational modes. For example, theSTA 106 can have a first operational mode referred to as an active mode.In the active mode, the STA 106 can always be in an “awake” state andactively transmit/receive data with the AP 104. Further, the STA 106 canhave a second operational mode referred to as a power save mode. In thepower save mode, the STA 106 can be in the “awake” state or a “doze” or“sleep” state where the STA 106 does not actively transmit/receive datawith the AP 104. For example, the receiver 212 and possibly DSP 220 andsignal detector 218 of the STA 106 can operate using reduced powerconsumption in the doze state. Further, in the power save mode, the STA106 can occasionally enter the awake state to listen to messages fromthe AP 104 (e.g., paging messages) that indicate to the STA 106 whetheror not the STA 106 needs to “wake up” (e.g., enter the awake state) at acertain time so as to be able to transmit/receive data with the AP 104.

Accordingly, in certain wireless communication systems 100, the AP 104can transmit paging messages to a plurality of STAs 106 in a power savemode in the same network as the AP 104, indicating whether or not thereis data buffered at the AP 104 for the STAs 106. The STAs 106 can alsouse this information to determine whether they need to be in an awakestate or a doze state. For example, if an STA 106 determines it is notbeing paged, it can enter a doze state. Alternatively, if the STA 106determines it can be paged, the STA 106 can enter an awake state for acertain period of time to receive the page and further determine when tobe in an awake state based on the page. Further, the STA 106 can stay inthe awake state for a certain period of time after receiving the page.In another example, the STA 106 can be configured to function in otherways when being paged or not being paged that are consistent with thisdisclosure.

In some aspects, paging messages can include a bitmap (not shown in thisfigure), such as a traffic identification map (TIM). In certain suchaspects, the bitmap can include a number of bits. These paging messagescan be sent from the AP 104 to STAs 106 in a beacon or a TIM frame. Eachbit in the bitmap can correspond to a particular STA 106 of a pluralityof STAs 106, and the value of each bit (e.g., 0 or 1) can indicate thestate the corresponding STA 106 should be in (e.g., doze state or awakestate) to be able to receive Buffed Units that the AP 104 has for thatparticular STA. Accordingly, the size of the bitmap can be directlyproportional to the number of STAs 106 in the wireless communicationssystem 100. Therefore, a large number of STAs 106 in the wirelesscommunications system 100 can result in a large bitmap.

In some aspects, STAs 106 that sleep for a long time may not wake up toread any TIM messages. For example, a STA 106 can decide to sleepthrough one or more TIM messages in an extended sleep mode. In thiscase, the STA 106 can advertise to the AP 104 that the STA 106 may notread any TIM messages. Accordingly, the AP 104 may not include thecorresponding identifiers in the TIM message. In various embodiments,the STAs 106 may notify the AP 104 that they may not wake up for one ormore TIM messages (i.e., that they are operating in the aforementionedpower saving mode) using a control message, or immediately duringassociation.

For STAs 106 that have notified the AP 104 in this manner, the AP 104may not include identifiers in the TIM message, even when it has BUsintended for them. STAs 106 can claim their BUs by sending a PS-Poll atany time to the AP 104. In an embodiment, AP 104 can immediately sendthe BU in response to the PS-Poll. In another embodiment, the AP 104 canrespond to the PS-Poll with an ACK, and deliver the BU at a later time.In yet another embodiment, the AP 104 may not immediately respond(neither with ACK nor with BU) to a PS-Poll. The AP 104 can insteadreply with a Cumulative ACK frame sent after a given scheduled timeafter the TIM message.

In various embodiments, the STA 106 can specify the waiting time todeliver the BU via the PS-Poll (for a dynamic indication), anassociation request, a probe request, and/or another management framesent to the AP (for a static indication). In other embodiments, the AP104 can specify the waiting time to deliver the BU via an ACK frame, aTIM element (for a dynamic indication), a beacon, an associationresponse, a probe response, or other management frames sent to the STA106 (for a static indication). The STA 106 can go to sleep for thewaiting time duration. The STA 106 can acknowledge correct reception ofthe BU by sending an ACK. The STA 106 can then go back to sleep.

FIG. 3 illustrates a plurality of partitioned paging messages 302transmitted by the AP 104 to STAs 106 in the wireless communicationsystem 100 of FIG. 1. As shown, time increases horizontally across thepage over the time axis 304. As shown, the AP 104 is configured totransmit a plurality of paging messages 302. The paging messages 302 canbe sent in a TIM frame, a beacon, or using some other appropriatesignaling. The STAs 106 can be configured to listen to one or more ofthe paging messages 302. Following the one or more paging messages 302,the STAs 106 can be configured to transmit requests to the AP 104 andreceive a response from the AP 104.

The paging process can result in a high number of STAs 106 receiving theone or more paging messages 302. For example, a high number of STAs 106in the same TIM can receive the one or more paging messages 302, whichcan lead to one or more STAs 106 contending to transmit requests to theAP 104 on the medium after the TIM. Accordingly, collisions resulting incorrupted data received by the AP 104 can occur in situations in whichat least two STAs 106 attempt to transmit requests to the AP 104 at ornearly at a same time.

FIG. 4 illustrates a polling request mechanism 400. The polling requestmechanism 400 shown can be used by the AP 104 and the STAs 106 in thewireless communication system 100 of FIG. 1. As shown, time increaseshorizontally across the page from time interval 426 to the time interval438. In an embodiment, the data delivery period can last for an integermultiple of time units (TUs). In an embodiment, each TU can besufficiently long to allow the STAs 402, 404, and 406 to performback-off, send PS-Poll, receive data and send an acknowledgement (ACK)to the AP 408. In one embodiment the AP 408 can include the TU durationin a TIM frame 409. The calculation of the TU by the AP 408 can takeinto account information regarding the Buffered Units (BUs) that the AP408 has to send to the paged STAs 402, 404, and 406. In one embodiment,the TU duration can account for the time to allow the correcttransmission of the longest possible BU to the intended paged STAs 402,404, and 406. In another embodiment, the TU can be the ratio between thetime during two consecutive TIM frames and the number of STAs indicatedin the first TIM map. In another embodiment, the TU can be the ratiobetween a data delivery period and a number of stations indicated in theTIM frame.

In general, after the transmission of a paging message, such as TIM 409,a time interval is reserved for the paged STAs 106. The reservation canbe achieved by transmitting a message (e.g., paging message, additionalmessage) to cause non-paged STAs to defer access to the medium for theduration of the reserved period. In some implementations, the deferredaccess can be achieved by setting a duration field value of a reservingframe so that non-paged STAs can set their network allocation vector(NAV). In other implementations, the deferred access can be achieved bysending an additional frame preceding or following the paging frame,where the additional frame indicates the duration of the reservedperiod. In an embodiment, the deferred access period can be the datadelivery period 411.

In some embodiments, one or more STAs 106 can ignore the NAV set duringthe contention period. For example, STAs 106 may be paged by the AP 104,as indicated in the TIM 409. Paged STAs 106 may ignore the previouslyset NAV. In an embodiment, ignoring the NAV can be based on anindication in the TIM 409 paging. When STAs 106 ignore the NAV, they canaccess the wireless medium, for example, to transmit PS-Poll requests.In other words, STAs 106 can refrain from obeying the NAV.

During the reserved time interval, the paged STAs 106 can send requeststo the AP 104 (e.g., Power Saving polls (PS-Poll) requests 412, 416, and420) and receive a response from the AP 104 (e.g., response 414, 418,and 422). The STAs 106 can also acknowledge the responses 414, 418, and422 via acknowledgements (ACKs) 415, 419, and 423. Multiple paged STAs106 can contend during the reserved time interval in accordance withvarious methods, as described herein. In some embodiments, STAs 106 thathave not been paged cannot contend during the reserved time interval.Once the reserved time interval is over, STAs 106 can start contendingto send the requests to the AP 104. In an embodiment, the AP 104 candetermine the duration of the reserved time interval. The reserved timeinterval should be sufficient for all the paged STAs 106 to sendrequests to the AP 104 and receive a response from the AP 104. By way ofexample, and not limitation, the duration of the reserved time intervalcan be a function of the number of paged STAs 106.

The polling request mechanism 400 illustrates an embodiment in whichSTAs 402, 404, and 406 can transmit requests, like PS-Polls 412, 416,and 420, to AP 408 in such a way so as to avoid collisions. STAs 402,404, and 406 can be similar to STAs 106 as described herein. In someembodiments, the STAs 402, 404, and 406 can transmit requests to the AP408 in a certain order. AP 408 can be similar to AP 104 as describedherein. The paging message, such as TIM 409, can implicitly orexplicitly define an ordering for the STAs 402, 404, and 406. Forexample if the TIM 409 bitmap indicates that both STA 402 and STA 404are paged, then the TIM 409 bitmap also implicitly or explicitlyindicates whether STA 402 is before or after STA 404. In an example, theorder could be determined by the order in which the paged STAs appear inthe bitmap representation. Consider a bitmap {0, 1, 0, 0, 1, 1}, wherethe STA associated with the bit in position 2 is assumed to be beforethe STA associated with the bit in position 5. In some implementations,the compressed bitmap can be expressed as list of STA identifiers. Inthis case the sequence in which the STA identifiers appear in the listcan determine the order. Consider the list {13, 25, 5, 22}, where theSTA associated with identifier “13” is assumed to come before STAidentified by “5.” In another aspect, the order can be derived from thevalue of the STA identifier irrespective of the message representation.In one aspect, the order can be derived from a hash of the STAidentifier. In another aspect the order can be derived by one or moreMost Significant Bits (MSB) of the STA identifier.

In some implementations, the position of the STA 402, 404, or 406 withinthe TIM 409 bitmap sequence can be a function of the position of the STA402, 404, or 406 as described above. The order can further be dependenton other indications, the indications being either included in thepaging message or assumed to be known at the STAs 402, 404, and/or 406.For example, the indication can include the Time Stamp Field (TSF)within the paging message (e.g., TIM 409). In such an implementation,the first STA can be the one whose identifier is set to “1” and has aposition within the TIM 409 bitmap sequence which is first in the orderafter the position associated with the 12 least significant bits (LSBs)of the TSF. Many other functions incorporating various indications canbe included to achieve a similar result as that based on the Time StampField. In various embodiments, the indications can include, for example,a scrambling seed, a FCS, a CRC, a TIM frame, and/or any hash functionof the partial or full content of the packet, including the TIM frames.One beneficial result of including the Time Stamp field in thecomputation of the order is that the order can be changed at eachtransmission, provided that the portion of the used Time Stamp Field isdifferent at each transmission.

In some implementations, the sender of the paging message can determinethe order of the paged STAs according to any criteria including theusage of the ordering information. For example the sender, AP 408, canorder the STAs 402, 404, and 406 based on their QoS requirements, powersaving requirements, or other performance parameters. It can bedesirable in some implementations for the sender of the paging messageto include in the message an explicit indication of the order. Thisexplicit indication of the order may not be based on the TIM 409 bitmap,but rather on other factors as described herein.

In one embodiment, the paging message can include a “time unitmultiplier” that can indicate to the STA 106 how many time units to waitbefore waking up. The STAs 402, 404, and 406 can multiply the time unitmultiplier by their ordinal number (starting at zero) within the TIM 409in order to compute a “wake up time.” In an embodiment, the wake up timecan be relative to the TIM 409. Therefore, the wake up time can indicatethe number of time units, after the TIM 409, which the STAs should waitbefore waking up. In the illustrated embodiment, the STA 402 has a wakeup time at the beginning of the time interval 426. The STA 404 has awake up time at the beginning of the time interval 432. STA 406 has awake up time at the beginning of the time interval 438. In variousembodiments, the AP 408 can communicate the time unit multiplier in oneor more of a beacon, a TIM beacon, the TIM 409, or any othercommunication. In one embodiment, the STAs 402, 404, and 406 can includea pre-set time unit multiplier.

For illustrative purposes only, and without limitation, FIG. 4 depicts apolling order wherein STA 402 is at the first position in the TIM 409(position 0), STA 404 is at the second position TIM 409 (position 1),and STA 406 is at the third position TIM 409 (position 2). First the AP408 transmits the TIM 409. As discussed above, the TIM 409 can indicatethat the AP 408 has buffered data ready for the STAs 402, 404, and 406.Moreover, the TIM 409 can indicate the ordering of the STAs 402, 404,and 406, and include the time unit multiplier. The STA 402 can multiplyits position 0 by the time unit multiplier to determine that it shouldwake up immediately after the TIM 409.

At the beginning of the time interval 426, the STA 402 wakes up. Each ofSTAs 402, 404, and 406 can be configured to defer for a back-off periodprior to accessing the medium to send the PS-Poll. The back-off can usea carrier sense multiple access with collision avoidance (CSMA/CA) basedmedium access procedure, such as the distributed coordination function(DCF) or the enhanced distributed channel access (EDCA) as defined inthe IEEE 802.11 standard using the highest priority access configuration(AC) parameters. In an embodiment, prior to back-off the STAs can stayawake for an additional Probe Delay time to sense any ongoingtransmissions. In time interval 426, the STA 402 transmits a PS-Pollrequest 412 to the AP 408. The AP 408 can send the response 414 to theSTA 402. The response 414 can include at least a portion of the buffereddata addressed to the STA 402. After successfully receiving the response414, the STA 402 can transmit an ACK 415 to the AP 408. Subsequently,the STA 402 can go back to sleep (or doze), for example until it wakesup again to receive the next TIM.

In certain operation modes, the STA 402 may not wake up at all TIMmessages. In these operation modes, the STA 402 may notify the AP thatthe STA 402 is awake and ready to receive data via the PS-Poll.

At the beginning of the time interval 432, the STA 404 wakes up. The STA404 can perform the back-off and then transmit a PS-Poll request 416 tothe AP 408. The AP 408 can send the response 418 to the STA 404. Theresponse 416 can include at least a portion of the buffered dataaddressed to the STA 404. After successfully receiving the response 416,the STA 404 can transmit an ACK 419 to the AP 408.

Similarly, at the beginning of the time interval 438, the STA 406 wakesup. The STA 406 can perform the back-off and then transmit a PS-Pollrequest 420 to the AP 408. The AP 408 can send the response 422 to theSTA 406. The response 422 can include at least a portion of the buffereddata addressed to the STA 406. After successfully receiving the response422, the STA 406 can transmit an ACK 423 to the AP 408.

In an embodiment, the AP 408 can set the NAV for the entire datadelivery period 411. In an embodiment, the AP 408 can set a Probe Delayto 0, thereby reducing the wake-up time. In an embodiment, however, itmay not be practical to set the NAV for the entire data delivery period411 or to eliminate the Probe Delay. In another embodiment, anotherpolling request mechanism can be used, wherein the AP 408 does not setthe NAV for the entire data delivery period or eliminate the ProbeDelay. For example, the wireless communication system 100 can use thepolling mechanism described herein with respect to FIGS. 5A-B.

FIG. 5B illustrates another polling request mechanism 550. The pollingrequest mechanism 550 shown can be used by the AP 104 and the STAs 106in the wireless communication system 100 of FIG. 1. The polling requestmechanism 550 is similar to the polling request mechanism 400 of FIG. 4.However, in the polling request mechanism 550, the TIM interval isdivided into two periods: a contention period 510 and a data deliveryperiod 511.

As shown in FIG. 5B, time increases horizontally across the page fromthe contention period 510 to the data delivery period 511, and withinthe data delivery period 511 from the time interval 526 to the timeinterval 538. In an embodiment, the data delivery period 511 can lastfor an integer multiple of time units (TUs). In an embodiment, each TUcan be sufficiently long to allow the AP 508 to perform back-off, sendBuffered Units, and receive the ACK from the paged STAs 502, 504, and506. In one embodiment the AP 508 can include the TU duration in a TIMframe 509. The calculation of the TU by the AP 508 can take into accountinformation regarding the Buffered Units that the AP has to send to thepaged STAs. In one embodiment the TU can account for the time to allowthe correct transmission of the longest possible BU to the intendedpaged STAs 502, 504, and 506. In one embodiment, the contention periodcan be divided into multiple intervals 526, 532, and 538. In anembodiment, the interval duration in the contention period 510 can becalculated to account for the back-off duration, transmission of thePS-Poll and reception of the ACK by a paged STA. In another embodimentthe interval duration can be included in the TIM frame 509 by the AP508. In another embodiment the TU can be the ratio between the timeduring two consecutive TIM frames and the number of STAs indicated inthe first TIM map.

In general, after the transmission of a paging message, such as TIM 509,a time interval is reserved for the paged STAs 106. The reservation canbe achieved by transmitting a message (e.g., paging message, additionalmessage) to cause non-paged STAs to defer access to the medium for theduration of the reserved period. In some implementations, the deferredaccess can be achieved by setting a duration field value of a reservingframe so that non-paged STAs can set their network allocation vector(NAV). Upon reception of a TIM message indicating that the STA is paged,the STA 106 can reset the NAV. In another embodiment, the STA can resetthe NAV only when the NAV was set by the same AP 104 that sent out theTIM message. In other implementations, the deferred access can beachieved by sending an additional frame preceding or following thepaging frame, where the additional frame indicates the duration of thereserved period. For example, the AP 508 can set the NAV by transmittinga clear-to-send-to-self (CTS-to-self) packet preceding the TIM 509. Inan embodiment, the AP 508 can set the NAV to around 20 to 40 ms. In theillustrated embodiment, the deferred access period is the contentionperiod 510.

During the contention period 510, the paged STAs 106 candeterministically send requests to the AP 104 (e.g., Power Saving polls(PS-Poll) requests 512, 516, and 520) and receive an ACK from the AP 104(e.g., ACKs 513, 517, and 521). Multiple paged STAs 106 can contendduring the reserved time interval in accordance with various methods, asdescribed herein. In some embodiments, STAs 106 that have not been pagedcannot contend during the reserved time interval. Once the contentionperiod 510 is over, unpaged STAs 106 can start contending to send therequests to the AP 104. In an embodiment, the AP 104 can determine theduration of the contention period 510. The contention period 510 shouldbe sufficient for all the paged STAs 502, 504, and 506 to send requeststo the AP 508. By way of example, and not limitation, the duration ofthe reserved time interval can be a function of the number of paged STAs502, 504, and 506.

In the illustrated embodiment, the paged STAs 502, 504, and 506 areconfigured to send the requests 512, 516, and 520 to the AP 508 in acertain order. As in the polling request mechanism 400 (FIG. 4), thepaging message, such as TIM 509, can implicitly or explicitly define anordering for the STAs 502, 504, and 506. For example if the TIM 509bitmap indicates that both STA 502 and STA 504 are paged, then the TIM509 bitmap also implicitly or explicitly indicates whether STA 502 isbefore or after STA 504. In an example, the order could be determined bythe order in which the paged STAs appear in the bitmap representation.In some implementations, the compressed bitmap can be expressed as listof STA identifiers. In another aspect, the order can be derived from thevalue of the STA identifier irrespective of the message representation.

In some implementations, the position of the STA 502, 504, or 506 withinthe TIM 509 bitmap sequence can be a function of the position of the STA502, 504, or 506 as described above. The order can further be dependenton other indications, the indications being either included in thepaging message or assumed to be known at the STAs 502, 504, and/or 506.For example, the indication can include the Time Stamp Field (TSF)within the paging message (e.g., TIM 509). In such an implementation,the first STA can be the one whose identifier is set to “1” and has aposition within the TIM 509 bitmap sequence which is first in the orderafter the position associated with the 12 least significant bits (LSBs)of the TSF. Many other functions incorporating various indications canbe included to achieve a similar result as that based on the TSF. Onebeneficial result of including the TSF in the computation of the orderis that the order can be changed at each transmission, provided that theportion of the used TSF is different at each transmission.

In some implementations, the sender of the paging message can determinethe order of the paged STAs according to any criteria including theusage of the ordering information. For example the sender, AP 508, canorder the STAs 502, 504, and 506 based on their QoS requirements, powersaving requirements, or other performance parameters. It can bedesirable in some implementations for the sender of the paging messageto include in the message an explicit indication of the order. Thisexplicit indication of the order may not be based on the TIM 509 bitmap,but rather on other factors as described herein.

In one embodiment, the paging message can include a contention “timeunit multiplier” that can indicate to the STA 106 how many time units towait before waking up to send a request during the contention period510. In one embodiment, the contention time unit multiplier can beimplicit (sufficient to allow transmission of the PS-Poll and ACK, and amaximum back-off time) or can be signaled by in another frame sent bythe AP 104 to the STAs 106. The STAs 502, 504, and 506 can multiply thecontention time unit multiplier by their ordinal number (starting atzero) within the TIM 509 in order to compute a “wake up time.” In anembodiment, the wake up time can be relative to the TIM 509. Therefore,the wake up time can indicate the number of time units, after the startof the contention period 510, which the STAs should wait before wakingup.

During the data delivery period 511, the paged STAs 106 can receive aresponse from the AP 104 (e.g., response 514, 518, and 522), and sendACKs to the AP 104 (e.g., ACKs 515, 519, and 523). In one embodiment,the paging message can include a data delivery “time unit multiplier”that can indicate to the STA 106 how many time units to wait beforewaking up to receive a response during the data delivery period 511. Thedata delivery time unit multiplier can be different from the contentionperiod time unit multiplier. The STAs 502, 504, and 506 can multiply thedata delivery time unit multiplier by their ordinal number (starting atzero) within the TIM 509 in order to compute a “wake up time.” In anembodiment, the wake up time can be relative to the TIM 509, to the endof the contention period 510, or to the start of the data deliveryperiod 511. Therefore, the wake up time can indicate the number of timeunits, after the start of the data delivery period 511, which the STAsshould wait before waking up.

In the illustrated embodiment, the STA 502 has a wake up time at thebeginning of the time interval 526. The STA 504 has a wake up time atthe beginning of the time interval 532. STA 506 has a wake up time atthe beginning of the time interval 538. In various embodiments, the AP508 can communicate the various time unit multipliers in one or more ofa beacon, a TIM beacon, the TIM 509, or any other communication. In oneembodiment, the STAs 502, 504, and 506 can include pre-set time unitmultipliers.

For illustrative purposes only, and without limitation, FIG. 5B depictsa polling order wherein STA 502 is at the first position in the TIM 509(position 0), STA 504 is at the second position TIM 509 (position 1),and STA 506 is at the third position TIM 509 (position 2). First the AP508 transmits the TIM 509. As discussed above, the TIM 509 can indicatethat the AP 508 has buffered data ready for the STAs 502, 504, and 506.Moreover, the TIM 509 can indicate the ordering of the STAs 502, 504,and 506, and include the time unit multiplier. The STA 502 can multiplyits position 0 by the time unit multiplier to determine that it shouldwake up immediately after the TIM 509.

At the beginning of the contention period 510, the STA 502 wakes up.Each of STAs 502, 504, and 506 can be configured to wait a back-offperiod. The back-off can use a carrier sense multiple access withcollision avoidance (CSMA/CA) based medium access procedure, such as thedistributed coordination function (DCF) or the enhanced distributedchannel access (EDCA) as defined in the IEEE 802.11 standard. In anembodiment, prior to the back-off, the STAs 502, 504, and 506 can stayawake for an additional Probe Delay time to sense any ongoingtransmissions. In another embodiment, the Probe Delay can be eliminated.In time interval 526, the STA 502 transmits a PS-Poll request 512 to theAP 508. The AP 508 can send the ACK 513 to the STA 502. In anembodiment, the ACK 513 can include a specific wake-up time at which theSTA 502 should wake up to receive the response 514. In an embodiment,the STA 502 can use the wake-up time included in the ACK 513 instead ofcomputing a wake-up time based on a time unit multiplier. In anotheraspect, the STAs 502 can indicate its wake-up time to the AP 508 via therequest 512. Subsequently, the STA 502 can go back to sleep (or doze),for example until it wakes up again to receive the response 514.

Then, the STA 504 wakes up. The STA 504 can perform the back-off andthen transmit a PS-Poll request 516 to the AP 508. The AP 508 can sendthe ACK 517 to the STA 504. The STA 504 can then sleep or doze until thebeginning of time interval 532. Similarly, the STA 506 wakes up. The STA506 can perform the back-off and then transmit a PS-Poll request 520 tothe AP 508. The AP 508 can send the ACK 521 to the STA 506. The STA 506can then sleep or doze until the beginning of time interval 538. Hence,according to one embodiment of the power saving mechanism describedabove, the AP 508, which responds to the PS-Poll with an ACK shall notsend BUs to any of the STAs 502, 504, 506 before their scheduled wake-uptimes.

At the beginning of the data delivery period 511, at time interval 526,the STA 502 wakes up. The AP 508 can send the response 514 to the STA502. The response 514 can include at least a portion of the buffereddata addressed to the STA 502. After successfully receiving the response514, the STA 502 can transmit an ACK 515 to the AP 508. Subsequently,the STA 502 can go back to sleep (or doze), for example until it wakesup again to receive the next TIM.

At the beginning of the time interval 532, the STA 504 wakes up. The AP508 can send the response 518 to the STA 504. The response 516 caninclude at least a portion of the buffered data addressed to the STA504. After successfully receiving the response 516, the STA 504 cantransmit an ACK 519 to the AP 508. Similarly, at the beginning of thetime interval 538, the STA 506 wakes up. The AP 508 can send theresponse 522 to the STA 506. The response 522 can include at least aportion of the buffered data addressed to the STA 506. Aftersuccessfully receiving the response 522, the STA 506 can transmit an ACK523 to the AP 508.

FIG. 5B illustrates another polling request mechanism 550. The pollingrequest mechanism 550 shown can be used by the AP 104 and the STAs 106in the wireless communication system 100 of FIG. 1. The polling requestmechanism 550 is similar to the polling request mechanism 500 of FIG.5A. However, in the polling request mechanism 550, the AP 104 does notimmediately respond to the PS-Poll 512, 516, and 520. Instead, the AP104 replies with a cumulative ACK 560 frame, sent at the end of (orafter) the contention period 510.

In the illustrated embodiment, during the contention period 510, thepaged STAs 106 can send requests to the AP 104 (e.g., Power Saving polls(PS-Poll) requests 512, 516, and 520) and receive a cumulative ACK 560from the AP 104. The PS-Poll requests 512, 516, and 520 can eachindicate whether the AP 104 should respond with an immediate ACK (seeFIG. 5A) or the cumulative ACK 560. In various embodiments, thecumulative ACK 560 can include one or more indications, as discussedbelow.

In one embodiment, the cumulative ACK 560 can contain multipleacknowledging indications, each indicating whether at least one PS-Poll512, 516, or 520 was received from the STA 106. The STA 106 can belongto a set of STAs. In another embodiment, the acknowledging indicationscan indicate whether the AP 104 received no PS-Poll 512, 516 from any ofthe STAs 106 in the set of STA. The methods for representing themultiple acknowledging indications in the cumulative ACK 560 can be sameor similar to the methods used to represent the TIM map in a TIM messageand can include any method of compressed representation. In particularthe representation can implicitly or explicitly define an ordering amongthe STAs 106. The ordering can be further based on QoS indications sentby the STAs 106 in the PS-Poll.

In one embodiment, the set of STAs can include all the STAs 106associated with the AP 104. In this embodiment, the acknowledgingindications can be a local identifier of the STA 106 or a globalidentifier (e.g., MAC address) of the STA 106. In another embodiment,the set of STAs can include all the STAs 106 for which the preceding TIMmessage 509 indicated the existence of a BU intended for that STA 106.In this embodiment, the acknowledging indications can identify the STA106 within the set of STAs by indicating the position of the STA 106 inthe list (or map) of STAs for which the AP 104 has a BU, as indicated bythe preceding TIM message 509.

In another embodiment, the set of STAs can include all the STAs 106 forwhich the preceding TIM message 509 was intended to provide anindication that the AP 104 has a BU for the STA 106. In this embodiment,the acknowledging indications can identify the STA 106 within the set ofSTAs for which the TIM 509 provided indication of both a present orabsent BU, by indicating the position of the STA 106 as provided in thepreceding TIM message 509.

In one embodiment, cumulative ACK 560 can include an indicationassociated with each of the time intervals 526, 532, and 538. Theindication of the time intervals 526, 532, and 538 for a STA 106 canbased on the position of the acknowledging indication for STA 106, theposition being determined based on ordering defined by the method ofrepresentation of the multiple acknowledging indications. The timeintervals can be further dependent on a Time Unit indication included inthe same Cumulative ACK. In another embodiment, the cumulative ACK 560can contain an identifier that identifies the corresponding TIM messageto which the acknowledgement indications refer. The identifier caninclude one or more of the sequence number, Time Stamp Field, and analternative identifier of the management frame carrying thecorresponding TIM message.

In an embodiment, the AP 104 can send the cumulative ACK 109 at the endof the protected poll interval 510. In another embodiment, the AP 104can send the cumulative ACK 560 at a time indication included in the TIMmessage 509. In another embodiment, the AP 104 can send the cumulativeACK 560 at the time where the next TIM message is expected for the setof STAs. Accordingly, the STAs can wake up only at the time where a TIMmessage is expected, instead of waking up at distinct times forreceiving the TIM message and the cumulative ACK 560. In this embodimentthe cumulative ACK 560 can acknowledge the reception of PS-Polls 512,516, and 520 sent in response to the previous TIM message. Moreover, theAP 104 can send the cumulative ACK 560 as a frame immediately before orafter the TIM element. In another embodiment, the AP 104 can send thecumulative ACK 560 in the same frame as the TIM message 509. In oneembodiment, the cumulative ACK 560 can be an Information Element.

FIG. 6 illustrates an exemplary non-polling mechanism 600. Thenon-polling mechanism 600 shown can be used by the AP 104 and the STAs106 in the wireless communication system 100 of FIG. 1. The non-pollingmechanism 600 is similar to the polling request mechanism 400 of FIG. 4.However, in the polling request mechanism 600, the STAs 602, 604, and606 do not send requests such as the requests 412, 416, and 420 shown inFIG. 4. Instead, the STAs 602, 604, and 606 wake up at the appropriatetime to receive the data 614, 618, and 622. In an embodiment, thewireless communication system 100 can operate according to thenon-polling mechanism 600 in situations where, for example, the full TIMindication map is sent across multiple fragments at different times, sothat the paging information for a STA 602, 604, or 606 is present onlyin some of the fragments. In addition, the AP 608 can command the pagedSTAs 602, 604, and 606 to be awake at their designated wake up times.Note that if the AP 608 can safely assume the STA 602, 604, or 606 isawake at designated time, the STA 602, 604, or 606 need not send aPS-Poll to the AP 608 to notify that it is awake. A STA 602, 604, or 606operating in this operation mode does not send PS-Poll to AP 608.

The polling request mechanism 600 illustrates an embodiment in whichSTAs 602, 604, and 606 can receive the data 614, 618, and 622 withoutsending requests such as PS-Polls so as to avoid collisions. STAs 602,604, and 606 can be similar to STAs 106 as described herein. In someembodiments, the STAs 602, 604, and 606 can receive data from the AP 608in a certain order. AP 608 can be similar to AP 104 as described herein.The paging message, such as TIM 609, can implicitly or explicitly definean ordering for the STAs 602, 604, and 606. For example if the TIM 609bitmap indicates that both STA 602 and STA 604 are paged, then the TIM609 bitmap also implicitly or explicitly indicates whether STA 602 isbefore or after STA 604. In an example, the order could be determined bythe order in which the paged STAs appear in the bitmap representation.In some implementations, the compressed bitmap can be expressed as listof STA identifiers. In this case the sequence in which the STAidentifiers appear in the list can determine the order. In anotheraspect, the order can be derived from the value of the STA identifierirrespective of the message representation.

In some implementations, the position of the STA 602, 604, or 606 withinthe TIM 609 bitmap sequence can be a function of the position of the STA602, 604, or 606 as described above. The order can further be dependenton other indications, the indications being either included in thepaging message or assumed to be known at the STAs 602, 604, and/or 606.For example, the indication can include the Time Stamp Field (TSF)within the paging message (e.g., TIM 609). In such an implementation,the first STA can be the one whose identifier is set to “1” and has aposition within the TIM 609 bitmap sequence which is first in the orderafter the position associated with the 12 least significant bits (LSBs)of the TSF. Many other functions incorporating various indications canbe included to achieve a similar result as that based on the TSF. Onebeneficial result of including the TSF in the computation of the orderis that the order can be changed at each transmission, provided that theportion of the used TSF is different at each transmission.

In some implementations, the sender of the paging message can determinethe order of the paged STAs according to any criteria including theusage of the ordering information. For example the sender, AP 608, canorder the STAs 602, 604, and 606 based on their QoS requirements, powersaving requirements, or other performance parameters. It can bedesirable in some implementations for the sender of the paging messageto include in the message an explicit indication of the order. Thisexplicit indication of the order may not be based on the TIM 609 bitmap,but rather on other factors as described herein.

In one embodiment, the paging message can include a “time unitmultiplier” that can indicate to the STA 106 how many time units to waitbefore waking up. The STAs 602, 604, and 606 can multiply the time unitmultiplier by their ordinal number (starting at zero) within the TIM 609in order to compute a “wake up time.” In one embodiment, the time unitmultiplier can be equal to a beacon period divided by a total number ofTIM bits set. In one embodiment, the STAs 602, 604, and 606 candetermine their order in a rotating manner. For example, the STAs 602,604, and 606 can calculate their order in the transmission sequence (j)as j=(i+tsf) mod n, where I is the order in the TIM, tsf is the value ofa TSF field in the TIM frame, and n is the total number of TIM bits thatare set.

In an embodiment, the wake up time can be relative to the TIM 609.Therefore, the wake up time can indicate the number of time units, afterthe TIM 609, which the STAs should wait before waking up. In theillustrated embodiment, the STA 602 has a wake up time at the beginningof the time interval 626. The STA 604 has a wake up time at thebeginning of the time interval 632. STA 606 has a wake up time at thebeginning of the time interval 638. In various embodiments, the AP 608can communicate the time unit multiplier in one or more of a beacon, aTIM beacon, the TIM 609, or any other communication. In one embodiment,the STAs 602, 604, and 606 can include a pre-set time unit multiplier.

For illustrative purposes only, and without limitation, FIG. 6 depicts adata transmission order wherein STA 602 is at the first position in theTIM 609 (position 0), STA 604 is at the second position TIM 609(position 1), and STA 606 is at the third position TIM 609 (position 2).First the AP 608 transmits the TIM 609. As discussed above, the TIM 609can indicate that the AP 608 has buffered data ready for the STAs 602,604, and 606. Moreover, the TIM 609 can indicate the ordering of theSTAs 602, 604, and 606, and include the time unit multiplier. The STA602 can multiply it's position 0 by the time unit multiplier todetermine that it should wake up immediately after the TIM 609.

At the beginning of the time interval 626, the STA 602 wakes up. The AP608 can send the data 614 to the STA 602. The response 614 can includeat least a portion of the buffered data addressed to the STA 602. Aftersuccessfully receiving the data 614, the STA 602 can transmit an ACK 615to the AP 608. Subsequently, the STA 602 can go back to sleep (or doze),for example until it wakes up again to receive the next TIM.

At the beginning of the time interval 632, the STA 604 wakes up. The AP608 can send the data 618 to the STA 604. The response 616 can includeat least a portion of the buffered data addressed to the STA 604. Aftersuccessfully receiving the data 616, the STA 604 can transmit an ACK 619to the AP 608.

Similarly, at the beginning of the time interval 638, the STA 606 wakesup. The AP 608 can send the data 622 to the STA 606. The response 622can include at least a portion of the buffered data addressed to the STA606. After successfully receiving the data 622, the STA 606 can transmitan ACK 623 to the AP 608.

In an embodiment, the wireless communication system 100 can beconfigured to selectively operate using two or more of the pollingrequest mechanism 400, the polling request mechanism 550, and thepolling request mechanism 600. For example, the AP 104 can include oneor more indication bits in the TIM frame setting an operation mode. Inone embodiment, the AP 104 can implicitly communicate the operationmode. For example, all paged STAs 106 can stay awake for the firstPS-Poll/request exchange. If the AP responds to the first request withan ACK, then the paged STAs 106 can operate according to the pollingrequest mechanism 550. Otherwise, the STAs 106 can operate according tothe polling request mechanism 400, for example.

In various embodiments, the wireless communication system 100 can beconfigured to jointly operate using two or more of the polling requestmechanism 400, the polling request mechanism 550, the non-pollingmechanism 600, and another polling request mechanism. For example, theSTAs 106 can communicate to the AP 104 which mechanism they are going touse. The AP can set parameters in accordance with the mechanism selectedby the STAs 106.

For example, in one embodiment, the STA 106 can indicate to the AP 104which power save operation mode it is going to use by sending a messageincluded in a management frame such as association request or a proberequest. In one embodiment, a 1 or 2 bit indication can be included inan Information Element that indicates a capability of the STA 106 (suchas, for example, HT Capabilities, VHT Capabilities, and/or ExtendedCapabilities), or that indicates an operating parameter of the STA 106(such as, for example, a HT Operating element and/or a VHT operatingelement).

In one embodiment, the AP 104 can accept the operating mode indicated bythe STA 106 and operate accordingly. In another embodiment, the AP 104can deny association STAs 106 indicating a particular operating mode. Inone embodiment the AP 104 can indicate allowed operation modes in beaconframes, probe response frames, and/or association response frames.

FIG. 7 is a flowchart of a process 700 for reducing collisions in thewireless communications system of FIG. 1. Although the method offlowchart 700 is described herein with reference to the device 202discussed above with respect to FIG. 2, a person having ordinary skillin the art will appreciate that the method of flowchart 700 can beimplemented by any other suitable device. In an embodiment, the steps inflowchart 700 can be performed by the processor 204 in conjunction withthe transmitter 210, the receiver 212, and the memory 206. Although themethod of flowchart 700 is described herein with reference to aparticular order, in various embodiments, blocks herein can be performedin a different order, or omitted, and additional blocks can be added.

First, at block 702, the wireless device 202 receives a paging messagefrom the AP 104, via the receiver 212. As discussed above with respectto FIGS. 4-6, the paging message can include an ordering and amultiplier. In an embodiment, the wireless device 202 can receive theordering and/or the multiplier from another communication, or the valuescan be preset.

Next, at block 704, the wireless device 202 determines a first wake-uptime based on the ordering and the multiplier. For example, theprocessor 204 can determine the order of the wireless device 202 withina TIM. The processor 204 can multiply the order (which can start atzero) by the multiplier. The result can be the wake-up time, in timeunits after receipt of the TIM. The wireless device 202 can sleep ordose until the determined wake-up time.

Then, at block 706, the wireless device 202 can wake-up. In anembodiment, the wireless device 202 can transmit a request for data, asdiscussed above with respect to FIGS. 4 and 5. In one embodiment, asdiscussed above with respect to FIGS. 5A-B, the wireless device 202 canreceive an acknowledgement to the request for data, and go back to sleepuntil another wake-up time at which time data will be received. Inanother embodiment, the wireless device 202 does not transmit a requestfor data, as discussed above with respect to FIG. 6.

Finally, at block 708, the wireless device receives the data from the AP104. In an embodiment, the wireless device 202 can send anacknowledgement to the AP 104. The data can be all or part of databuffered at the AP 104, and addressed to the wireless device 202.

FIG. 8 is a functional block diagram of an exemplary wireless device 800that can be employed within the wireless communication system 100. Thedevice 800 comprises means 802 for receiving a paging message includingan ordering and a multiplier, means 804 for determining a first wake-uptime based on the ordering and the multiplier, means 806 for waking upat the determining wake-up time, and means 808 for receiving data.

The means 802 for receiving a paging message including an ordering and amultiplier can be configured to perform one or more of the functionsdiscussed above with respect to the block 702 illustrated in FIG. 7. Themeans 802 for receiving a paging message including an ordering and amultiplier can correspond to one or more of the receiver 212, theprocessor 204, the transceiver 214, and the memory 206, discussed abovewith respect to FIG. 2. The means 804 for determining a first wake-uptime based on the ordering and the multiplier can be configured toperform one or more of the functions discussed above with respect to theblock 804 illustrated in FIG. 7. The means 804 for determining a firstwake-up time based on the ordering and the multiplier can correspond toone or more of the processor 204 and the memory 206, discussed abovewith respect to FIG. 2.

The means 806 for waking up at the determining wake-up time can beconfigured to perform one or more of the functions discussed above withrespect to the block 706 illustrated in FIG. 7. The means 806 for wakingup at the determining wake-up time can correspond to one or more of thereceiver 212, the processor 204, the transceiver 214, and the memory206, discussed above with respect to FIG. 2. The means 808 for receivingdata can be configured to perform one or more of the functions discussedabove with respect to the block 708 illustrated in FIG. 7. The means 808for receiving data can correspond to one or more of the receiver 212,the processor 204, the transceiver 214, and the memory 206, discussedabove with respect to FIG. 2.

As used herein, the term “determining” encompasses a wide variety ofactions. For example, “determining” can include calculating, computing,processing, deriving, investigating, looking up (e.g., looking up in atable, a database or another data structure), ascertaining and the like.Also, “determining” can include receiving (e.g., receiving information),accessing (e.g., accessing data in a memory) and the like. Also,“determining” can include resolving, selecting, choosing, establishingand the like. Further, a “channel width” as used herein can encompass orcan also be referred to as a bandwidth in certain aspects.

As used herein, a phrase referring to “at least one of” a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: a, b, or c” is intended to cover: a, b, c,a-b, a-c, b-c, and a-b-c.

The various operations of methods described above can be performed byany suitable means capable of performing the operations, such as varioushardware and/or software component(s), circuits, and/or module(s).Generally, any operations illustrated in the Figures can be performed bycorresponding functional means capable of performing the operations.

The various illustrative logical blocks, modules and circuits describedin connection with the present disclosure can be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array signal (FPGA) or other programmable logic device(PLD), discrete gate or transistor logic, discrete hardware componentsor any combination thereof designed to perform the functions describedherein. A general purpose processor can be a microprocessor, but in thealternative, the processor can be any commercially available processor,controller, microcontroller or state machine. A processor can also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

In one or more aspects, the functions described can be implemented inhardware, software, firmware, or any combination thereof. If implementedin software, the functions can be stored on or transmitted over as oneor more instructions or code on a computer-readable medium.Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage media can be anyavailable media that can be accessed by a computer. By way of example,and not limitation, such computer-readable media can include RAM, ROM,EEPROM, CD-ROM or other optical disk storage, magnetic disk storage orother magnetic storage devices, or any other medium that can be used tocarry or store desired program code in the form of instructions or datastructures and that can be accessed by a computer. Also, any connectionis properly termed a computer-readable medium. For example, if thesoftware is transmitted from a website, server, or other remote sourceusing a coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared, radio,and microwave, then the coaxial cable, fiber optic cable, twisted pair,DSL, or wireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Thus, in some aspects computer readable medium can includenon-transitory computer readable medium (e.g., tangible media). Inaddition, in some aspects computer readable medium can includetransitory computer readable medium (e.g., a signal). Combinations ofthe above should also be included within the scope of computer-readablemedia.

The methods disclosed herein include one or more steps or actions forachieving the described method. The method steps and/or actions can beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isspecified, the order and/or use of specific steps and/or actions can bemodified without departing from the scope of the claims.

The functions described can be implemented in hardware, software,firmware or any combination thereof. If implemented in software, thefunctions can be stored as one or more instructions on acomputer-readable medium. A storage media can be any available mediathat can be accessed by a computer. By way of example, and notlimitation, such computer-readable media can include RAM, ROM, EEPROM,CD-ROM or other optical disk storage, magnetic disk storage or othermagnetic storage devices, or any other medium that can be used to carryor store desired program code in the form of instructions or datastructures and that can be accessed by a computer. Disk and disc, asused herein, include compact disc (CD), laser disc, optical disc,digital versatile disc (DVD), floppy disk, and Blu-ray® disc where disksusually reproduce data magnetically, while discs reproduce dataoptically with lasers.

Thus, certain aspects can include a computer program product forperforming the operations presented herein. For example, such a computerprogram product can include a computer readable medium havinginstructions stored (and/or encoded) thereon, the instructions beingexecutable by one or more processors to perform the operations describedherein. For certain aspects, the computer program product can includepackaging material.

Software or instructions can also be transmitted over a transmissionmedium. For example, if the software is transmitted from a website,server, or other remote source using a coaxial cable, fiber optic cable,twisted pair, digital subscriber line (DSL), or wireless technologiessuch as infrared, radio, and microwave, then the coaxial cable, fiberoptic cable, twisted pair, DSL, or wireless technologies such asinfrared, radio, and microwave are included in the definition oftransmission medium.

Further, it should be appreciated that modules and/or other appropriatemeans for performing the methods and techniques described herein can bedownloaded and/or otherwise obtained by a user terminal and/or basestation as applicable. For example, such a device can be coupled to aserver to facilitate the transfer of means for performing the methodsdescribed herein. Alternatively, various methods described herein can beprovided via storage means (e.g., RAM, ROM, a physical storage mediumsuch as a compact disc (CD) or floppy disk, etc.), such that a userterminal and/or base station can obtain the various methods uponcoupling or providing the storage means to the device. Moreover, anyother suitable technique for providing the methods and techniquesdescribed herein to a device can be utilized.

It is to be understood that the claims are not limited to the preciseconfiguration and components illustrated above. Various modifications,changes and variations can be made in the arrangement, operation anddetails of the methods and apparatus described above without departingfrom the scope of the claims.

While the foregoing is directed to aspects of the present disclosure,other and further aspects of the disclosure can be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

What is claimed is:
 1. A method for reducing collisions in a wirelesscommunications network, the method comprising: receiving, at a wirelessdevice, a paging message comprising an ordering and a multiplier;determining a first wake-up time based on the ordering and themultiplier; waking up at the determined wake-up time; and receivingdata.
 2. The method of claim 1, wherein the multiplier indicates amultiple of time units comprising a ratio between a time during twoconsecutive TIM frames and a number of stations indicated in the firstTIM frame of the two consecutive TIM frames.
 3. The method of claim 1,wherein the multiplier indicates a multiple of time units comprising aratio between a data delivery period and a number of stations indicatedin the TIM frame.
 4. The method of claim 1, wherein the ordering isbased on a hash of a station identifier.
 5. The method of claim 1,wherein the ordering is based one or more most significant bits of astation identifier.
 6. The method of claim 1, further comprisingtransmitting a request for the data.
 7. The method of claim 6, furthercomprising: determining a second wake-up time; waking up at thedetermined second wake-up time; and receiving an acknowledgement to therequest for data, wherein the second wake-up time is earlier than thefirst wake-up time.
 8. The method of claim 7, wherein theacknowledgement comprises a cumulative acknowledgement.
 9. The method ofclaim 7, wherein determining the first wake-up time comprisesdetermining the first wake-up time based on the acknowledgement.
 10. Themethod of claim 7, wherein determining the first wake-up time comprisesdetermining the first wake-up time based on the ordering and themultiplier.
 11. The method of claim 7, wherein the request for datacomprises the determined first wake-up time.
 12. The method of claim 7,wherein the second wake-up time is during a contention period, and thefirst wake-up time is during a data delivery period.
 13. The method ofclaim 12, further comprising setting a network allocation vector duringthe contention period.
 14. The method of claim 13, further comprisingdetermining to ignore the network allocation vector set during thecontention period
 15. The method in claim 14, wherein ignoring thenetwork allocation vector is based on an indication in the TIM paging.16. The method of claim 1, further comprising transmitting anacknowledgement of the data.
 17. The method of claim 1, furthercomprising waiting a back-off period.
 18. The method of claim 1, furthercomprising transmitting an operating mode selection.
 19. A wirelessdevice configured to reduce collisions in a wireless communicationsnetwork, the wireless device comprising: a receiver configured toreceive a paging message comprising an ordering and a multiplier; aprocessor configured to: determine a first wake-up time based on theordering and the multiplier; wake up at the determined wake-up time; andreceive data.
 20. The wireless device of claim 19, wherein themultiplier indicates a multiple of time units comprising a ratio betweena time during two consecutive TIM frames and a number of stationsindicated in the first TIM frame of the two consecutive TIM frames. 21.The wireless device of claim 19, wherein the multiplier indicates amultiple of time units comprising a ratio between a data delivery periodand a number of stations indicated in the TIM frame.
 22. The wirelessdevice of claim 19, wherein the ordering is based on a hash of a stationidentifier.
 23. The wireless device of claim 19, wherein the ordering isbased one or more most significant bits of a station identifier.
 24. Thewireless device of claim 19, further comprising a transmitter configuredto transmit a request for the data.
 25. The wireless device of claim 24,wherein the processor is further configured to: determine a secondwake-up time; and wake up at the determined second wake-up time, whereinthe receiver is further configured to receive an acknowledgement to therequest for data, and the second wake-up time is earlier than the firstwake-up time.
 26. The wireless device of claim 25, wherein theacknowledgement comprises a cumulative acknowledgement.
 27. The wirelessdevice of claim 25, wherein the processor is configured to determine thefirst wake-up time based on the acknowledgement.
 28. The wireless deviceof claim 25, wherein the processor is configured to determine the firstwake-up time based on the ordering and the multiplier.
 29. The wirelessdevice of claim 25, wherein the request for data comprises thedetermined first wake-up time.
 30. The wireless device of claim 25,wherein the second wake-up time is during a contention period, and thefirst wake-up time is during a data delivery period.
 31. The wirelessdevice of claim 30, wherein the receiver is configured to receive anetwork allocation vector during the contention period.
 32. The wirelessdevice of claim 31, wherein the processor is configured to determine toignore the network allocation vector set during the contention period33. The wireless device in claim 32, wherein ignoring the networkallocation vector is based on an indication in the TIM paging.
 34. Thewireless device of claim 19, further comprising a transmitter configuredto transmit an acknowledgement of the data.
 35. The wireless device ofclaim 19, wherein the processor is further configured to wait a back-offperiod.
 36. The wireless device of claim 19, further comprising atransmitter configured to transmit an operating mode selection.
 37. Anapparatus for reducing collisions in a wireless communications network,the apparatus comprising: means for receiving a paging messagecomprising an ordering and a multiplier; means for determining a firstwake-up time based on the ordering and the multiplier; means for wakingup at the determined wake-up time; and means for receiving data.
 38. Theapparatus of claim 37, wherein the multiplier indicates a multiple oftime units comprising a ratio between a time during two consecutive TIMframes and a number of stations indicated in the first TIM frame of thetwo consecutive TIM frames.
 39. The apparatus of claim 37, wherein themultiplier indicates a multiple of time units comprising a ratio betweena data delivery period and a number of stations indicated in the TIMframe.
 40. The apparatus of claim 37, wherein the ordering is based on ahash of a station identifier.
 41. The apparatus of claim 37, wherein theordering is based one or more most significant bits of a stationidentifier.
 42. The apparatus of claim 37, further comprising means fortransmitting a request for the data.
 43. The apparatus of claim 42,further comprising: means for determining a second wake-up time; meansfor waking up at the determined second wake-up time; and means forreceiving an acknowledgement to the request for data, wherein the secondwake-up time is earlier than the first wake-up time.
 44. The apparatusof claim 43, wherein the acknowledgement comprises a cumulativeacknowledgement.
 45. The apparatus of claim 43, wherein means fordetermining the first wake-up time comprises means for determining thefirst wake-up time based on the acknowledgement.
 46. The apparatus ofclaim 43, wherein means for determining the first wake-up time comprisesmeans for determining the first wake-up time based on the ordering andthe multiplier.
 47. The apparatus of claim 43, wherein the request fordata comprises the determined first wake-up time.
 48. The apparatus ofclaim 43, wherein the second wake-up time is during a contention period,and the first wake-up time is during a data delivery period.
 49. Theapparatus of claim 48, further comprising means for setting a networkallocation vector during the contention period.
 50. The apparatus ofclaim 49, further comprising means for determining to ignore the networkallocation vector set during the contention period
 51. The apparatus inclaim 50, wherein ignoring the network allocation vector is based on anindication in the TIM paging.
 52. The apparatus of claim 37, furthercomprising means for transmitting an acknowledgement of the data. 53.The apparatus of claim 37, further comprising means for waiting aback-off period.
 54. The apparatus of claim 37, further comprising meansfor transmitting an operating mode selection.
 55. A non-transitorycomputer-readable medium comprising code that, when executed by one ormore processors, causes an apparatus to: receive a paging messagecomprising an ordering and a multiplier; determine a first wake-up timebased on the ordering and the multiplier; wake up at the determinedwake-up time; and receive data.
 56. The medium of claim 55, wherein themultiplier indicates a multiple of time units comprising a ratio betweena time during two consecutive TIM frames and a number of stationsindicated in the first TIM frame of the two consecutive TIM frames. 57.The medium of claim 55, wherein the multiplier indicates a multiple oftime units comprising a ratio between a data delivery period and anumber of stations indicated in the TIM frame.
 58. The medium of claim55, wherein the ordering is based on a hash of a station identifier. 59.The medium of claim 55, wherein the ordering is based one or more mostsignificant bits of a station identifier.
 60. The medium of claim 55,further comprising code that, when executed by one or more processors,causes the apparatus to transmit a request for the data.
 61. The mediumof claim 60, further comprising code that, when executed by one or moreprocessors, causes the apparatus to: determine a second wake-up time;wake up at the determined second wake-up time; and receive anacknowledgement to the request for data, wherein the second wake-up timeis earlier than the first wake-up time.
 62. The medium of claim 61,wherein the acknowledgement comprises a cumulative acknowledgement. 63.The medium of claim 61, further comprising code that, when executed byone or more processors, causes the apparatus to determine the firstwake-up time based on the acknowledgement.
 64. The medium of claim 61,further comprising code that, when executed by one or more processors,causes the apparatus to determine the first wake-up time based on theordering and the multiplier.
 65. The medium of claim 61, wherein therequest for data comprises the determined first wake-up time.
 66. Themedium of claim 61, wherein the second wake-up time is during acontention period, and the first wake-up time is during a data deliveryperiod.
 67. The medium of claim 66, further comprising code that, whenexecuted by one or more processors, causes the apparatus to set anetwork allocation vector during the contention period.
 68. The mediumof claim 67, further comprising code that, when executed by one or moreprocessors, causes the apparatus to determine to ignore the networkallocation vector set during the contention period
 69. The medium inclaim 68, wherein ignoring the network allocation vector is based on anindication in the TIM paging.
 70. The medium of claim 55, furthercomprising further comprising code that, when executed by one or moreprocessors, causes the apparatus to transmit an acknowledgement of thedata.
 71. The medium of claim 55, further comprising code that, whenexecuted by one or more processors, causes the apparatus to wait aback-off period.
 72. The medium of claim 55, further comprising codethat, when executed by one or more processors, causes the apparatus totransmit an operating mode selection.
 73. A method for reducingcollisions in a wireless communications network, the method comprising:transmitting, at a wireless device, an advertisement of an extendedsleep mode; sleeping through one or more paging messages of an accesspoint; transmitting a request for data; and receiving data.
 74. Themethod of claim 73, further comprising sleeping until a determinedwake-up time.
 75. The method of claim 74, wherein the request for datacomprises the wake-up time.
 76. The method of claim 74, furthercomprising receiving an acknowledgement to the request for data, theacknowledgement comprising the wake-up time.
 77. The method of claim 76,wherein the acknowledgment comprises a cumulative acknowledgement.
 78. Awireless device for reducing collisions in a wireless communicationsnetwork, the device comprising: a transmitter configured to transmit anadvertisement of an extended sleep mode; a processor configured to sleepthrough one or more paging messages of an access point, wherein thetransmitter is further configured to transmit a request for data; andwherein the device further comprises a receiver configured to receivedata.
 79. The wireless device of claim 7873, wherein the processor isfurther configured to sleep until a determined wake-up time.
 80. Thewireless device of claim 79, wherein the request for data comprises thewake-up time.
 81. The wireless device of claim 79, wherein the receiveris further configured to receive an acknowledgement to the request fordata, the acknowledgement comprising the wake-up time.
 82. The wirelessdevice of claim 81, wherein the acknowledgment comprises a cumulativeacknowledgement.
 83. An apparatus for reducing collisions in a wirelesscommunications network, the apparatus comprising: means for transmittingan advertisement of an extended sleep mode; means for sleeping throughone or more paging messages of an access point; means for transmitting arequest for data; and means for receiving data.
 84. The apparatus ofclaim 83, further comprising means for sleeping until a determinedwake-up time.
 85. The apparatus of claim 84, wherein the request fordata comprises the wake-up time.
 86. The apparatus of claim 84, furthercomprising means for receiving an acknowledgement to the request fordata, the acknowledgement comprising the wake-up time.
 87. The apparatusof claim 86, wherein the acknowledgment comprises a cumulativeacknowledgement.
 88. A non-transitory computer-readable mediumcomprising code that, when executed by one or more processors, causes anapparatus to: transmit an advertisement of an extended sleep mode; sleepthrough one or more paging messages of an access point; transmit arequest for data; and receive data.
 89. The medium of claim 88 furthercomprising code that, when executed by one or more processors, causesthe apparatus to sleep until a determined wake-up time.
 90. The mediumof claim 89, wherein the request for data comprises the wake-up time.91. The medium of claim 89, further comprising code that, when executedby one or more processors, causes the apparatus to receive anacknowledgement to the request for data, the acknowledgement comprisingthe wake-up time.
 92. The medium of claim 91, wherein the acknowledgmentcomprises a cumulative acknowledgement.